This invention relates to a shift assisting device and more particularly to an improved construction for a remote control operation including flexible transmitters.
The use of flexible transmitters such as bowden wire actuators is common for a wide variety of applications. One typical application for such mechanisms is in the shifting mechanism for a marine transmission. One or more bowden wire actuators are employed for transmitting motion from a remotely positioned shift control lever to a dog clutching element of the transmission. Frequently, these devices employ two flexible transmitters, one for transmitting motion from the control lever to a controlled lever and the other for transmitting movement from the controlled lever to the transmission dog clutching element. Frequently, a shift assisting mechanism is associated with this mechanism for slowing the speed of the engine to assist in shifting.
Although the use of flexible transmitters have a number of advantages, there are still some difficulties with the use of these devices. This is particularly true when two or more flexible transmitters are used in series, as aforedescribed. The reason for this is that it is difficult to match the movement of all of the connected components so that the degrees of travel are all the same. When one element moves father than the others, a force is transmitted to the flexible sheath which causes deflection of the components and which can cause wear. These problems may be best understood by reference to FIGS. 1 and 2. FIG. 1 shows a conventional type of mechanism of the type described and FIG. 2 shows one modification that has been adapted to the conventional systems in an effort to offset the problems aforenoted.
Referring first to FIG. 1, a conventional forward, neutral, reverse transmission of the type normally used in a marine outboard drive is indicated generally by the reference numeral 11. This transmission includes an input shaft 12 to which a driving bevel gear 13 is affixed. The driving bevel gear 13 drives a pair of counterrotating bevel gears 14 and 15 that are journaled on an output shaft 16. A dog clutching sleeve 17 has a splined connection to the output shaft 16 and is axially slidable along it for engagement of dog clutching teeth with corresponding dog clutching teeth on the gears 14 and 15. As a result, the shaft 16 may be driven in either forward or reverse directions. A pivotally supported lever 18 is connected to the dog clutching sleeves 17 for effecting its reciprocation along the shaft 16.
The operation of the dog clutching sleeve 17 is controlled by a remotely positioned shift control lever 19 that is connected to the wire element 21 of a first bowden wire actuator having a protective sheath 22. The bowden wire actuator 21 is connected at its other end to one end of a lever 23 that is supported for pivotal movement about a pivot pin 24 upon a shift assisting and detecting mechanism, to be described.
A second wire element 25 of a second bowden wire actuator is connected at one end to the lever 23 and at its other end to the lever 18. As a result, pivotal movement of the lever 19 will effect pivotal movement of the lever 23 and, accordingly, the lever 18 and reciprocation of the dog clutching sleeve 17.
The second wire actuator 25 is surrounded by a protective sheath 26 that is connected to one end of a shift detecting lever 27. When resistance to the shifting of the dog clutching sleeve 17 occurs, the lever 27 will pivot due to movement of the protective sheath 26 and a proximity switch 28 will be actuated. The proximity switch 28 is connected to a suitable mechanism for slowing the speed of the engine and assisting in shifting. The aforedescribed construction may be considered to be conventional and is well known in this art. For that reason, further description of it or the further illustration of its components are not believed necessary to understand the construction and operation of this invention.
As has been noted, the movement of the wire 21 is transmitted into movement of the wire 25 and when resistance occurs, the flexible sheath 26 will be deflected. However, frequently the range of movement of the control lever 19 does not exactly coincide with the range of pivotal movement of the lever 18 and it is normal that the lever 19 moves to a greater extent than will the lever 18. As a result, some flecture in the wire 25 must result to permit this difference in movement. This flecture of the wire along with the aforenoted flecture of the protective sheath 26 can cause wear, difficult operation and other disadvantages.
To partially offset these disadvantages, there has been proposed an arrangement wherein the end of the wire 25 has some form of lost motion connection to the lever 23 and this arrangement is shown in FIG. 2. In this figure, components which are substantially the same as the previously described construction have been identified by the same reference numerals.
In this construction, the end of the wire 25 that is connected to the lever 23 is received within a slot 31 of the lever. As a result, when the control moves through the distance 1, the lever 23 is pivoted through the arc with the pivotal connection of the wire 21 moving through the radius Rr. Since the point of connection of the wire 25 to the lever 23 is closer to the pivot point 24 of this lever, there will be a smaller radius Rd at this pivotal connection. However, if the lever 23 tends to move at a distance to cause the wire 25 to want to move a greater distance L--L', than the corresponding distance 1 of the lever 21, this may be accommodated through movement of the end of the wire 25 from the position a to the position a' along the slot 31. Hence, this device does somewhat reduce the loading on the mechanism. However, it does not fully accommodate all situations, particularly when there is play in both directions of the movement of the lever 19.
It is, therefore, a principal object of this invention to provide an improved shift assisting device.
It is a further object of this invention to provide an improved mechanism for the shifting of a marine transmission.
It is a yet further object of this invention to provide a shifting device for a mechanism embodying a wire transmitter wherein an arrangement is incorporated so as to prevent undue loading of the wire transmitter due to difference in range of movement of the control member from the controlled member.